Thorium dioxide sol and method of making the same



Patented July 18, 1933 UNITED STATES,

PATENT. OFFICE BUDOLF ZELLHANN, OF RADEIBE'UL-DBESDEN, GERMANY, ASSIGNOB IO I IABBIK VON HEYIOEN, A. G., O]? DBESDEN, GERMANY, A CORPORATION 01' I MANY enn- THOBIUM DIOXIDE SOL AND METHOD OF MAKING- THE sum 1T0 Drawing. Application filed August 12, 1980, Serial No. 474,882, and in Gcrmanylovcmbcr 18, 1889.

This invention relates to compounds for use as contrast mediums in X-ra-y photography, especially pyelography. It relates particularly to a stabilized colloidal thorium di- 5 oxide sol, which presents important advantages over the hitherto known unstabilized thorium dioxide of acid reaction, which, ow-

ingto their positive charge, coagulated or flocculated when brought into contact with m mucosal surfaces or body fluids, or when neutralized by addition'of alkali or other means.

The hitherto known unstabilized acid thorium dioxide sols are suitable for use as contrast mediums in X-ray photography of the surfaces of the intestine, as the thorium dioxidecoagulates on the surface, thereby providing a good contrast medium for relief pictures of said surfaces, as obvious from Bluebaum Frek & .Kalkbrenner Fortsch. der R0 cut enstra'hlemBd. 37, Heftl.

owever, for pyelographic use,- such unstabilized acid thorium dioxide sols could be used only with great danger, owing to the fact I thereby forming an unstabiliz'ed, positively charged acid reacting'thorium dioxide sol.

In the literature, so for instance in the well known textbookby Meyer-Iacobson, vol. I, 2nd part, page 907, the carbohydrates are classified:

I. Sugars not hydrolyzable= Mono-saccharides. H. Hydrolyzable carbohydrates= .Poly-saccharides.

a Hydrolyzable sugars.

b Polysaccharides other than sugars: starch, cellulose dextrin, etc. I have now found that if such a sol is combined with a colloidal substance selected from a group consisting of starch and the colloidal or semi-colloidal substances obtained therefrom by splitting the same, i. e. by hydrolysis, namely amylose, malto-dextrine, am lodextrine and commercialdextrine, and t e mix- -.amylose, malto ture is neutralized, the resultant product is i highly stable thorium dioxide sol, which may be admixed with all body fluids, or brought into contact with *mucosal surfaces with out change, such ascoagulation or flocculation. This protective function which dextrin even if alkaline exerts in this case is quite remarkable, in that-the materials which are ordinarily rateda's strong protective agents fail in this instance.

EwampZe.Into a 12% unstabilized,posithorium dioxide solution is to be sterilized,

i. e., by heating the same to 100 (3., the reaction turns weakly acid. This is avoided by trasts in pyelograp y, said process compris-- ing adding a colloidal soluble substance selected from a (group consistin of starch extrine, amylo extrine an commercial dextrine, to unstabilized pod. titiely charged acid reacting thorium dioxide so 2. The process of making thorium dioxide sol suitable for the lproduction of sharp contrasts in pyelograp y, said process comprising adding colloidal soluble splitting prod nets of starch to unstabilized, positively charged acid reacting'thorium dioxide sol.

3. The process of making thorium dioxide sol suitable for the production of sharp con- I trasts in pyelography, said process com 'rising adding dextrin to unstabilized, positively charged acid reacting thorium dioxide sol.

4. The process of making thoriumdioxide sol suitable for. the }production of sharp contrasts in pyelograp said process comprising adding a colloidal soluble-substance se-- lected from a group consistin of starch amylose, maltodextrine, amyl bextrine commercial dextrine, to unsta P0 tively charged acid reacting thorium dioxide adding a priori sufficient alkali metal hydroxitrasts in pyelograp commercial dextrine,

sol, and neutralizing the reaction product.

5. The process of making thorium dioxide sol suitable for the production of sharp contrasts in pyelography, said process comprising adding. colloidal soluble splitting prod-- ucts of starch to unstabilized, positively 1 tively charged acid reacting thorium sol, and adding alkaline metal hydroxide to aforesaid mixture until the same shows an alkaline reaction.

8. The process of making thorium dioxide sol suitable for the production of sharp contrasts in pyelography, said process comprising adding colloidal soluble splitting products .of starch to unstabilized, positively charged acid reacting thorium dioxide sol, and adding alkaline metal hydroxide to aforesaid mixture until the same shows an alkaline reaction. I

9. The process ofmaking thorium dioxide sol suitable for the production of sharp contrasts in pyelography, said rocess compris- 1 mg addin dextrin to unsta ilized positively char and a ding alkaline metal hydroxide to aforesaid mixture until the same shows an alkaline reaction. w

10. As a contrast medium in X-ray photography, especially in pyelography, thorium dioxide sol, stabilized by a colloidal soluble substance selected from a group consisting of starch, amylose, ,maltodextrine, am lodextrine and commercial dextrine, said t orium dioxide sol being of neutral reaction, miscible with all body fluids and contacting with ,inucosal surfaces without coagulation and flocculation.

11. As a contrast'medium in X-ray photography, especially in pyelography, thorium dioxide sol, stabilized by dextrin, thorium dioxide sol bein of neutral reaction, miscible with'all body uids and contacting with mucosal surfaces without coagulation and flocculation.

' RUDOLF ZELLMANN.

e acid reacting thorium dioxide sol, 7

said 

